Gas-cell fabric



p to dilute the buoyant fluid to *tioned above, gold heaters? skin has 40 -ployed. Without doubt this material is the Patented Nov. 13,1928.

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1,691,764, 1" OFFICE-4 KELLY, or axaon, onro, ASSIGNOR To rim eoonvnnit rum 8'. RUBBER coiuramz, or AKRON, onro, n' conro ATION on cam.

GAS-CELL FABRIC.

My invention relates to lighter-than-aircraft and it has particular relation to gas retain mediums employed therein.

The diject of m invention is to provide aninexpensive'yet 'ghly impermeable medium for retaining a buoyant fluid.

The problem of providing a suitablemedlum for retaining a gas has never been solved satisfactorily. This is due in part perhaps 10 to the fact that the requirements are very stringent and in part to the necessity of selecting an inexpensive material. To be satisfactory, the medium must not only be of minimum weight, but must be susceptible to flexing, changes in' temperature and in 'addition must have age-resisting qualities. Obviously, another important property which a fabric must possess is that of impermeabili especially with respect to the buoyant 2o flui On the other hand-a medium which will retain the buoyant fluid cannot be adapts ed if it is not impermeable to oxygen and. nitrogen. A less portant consideration, but nevertheless one that should not. be

.25 ignored, is that of the relative solubility of e severalrgases. For example, gold beat ers skin, which is highly impermeable to hydrogen and helium, has a tendency to dissolve oxygen and nitrogen, and by so doing such extent as to necessitate purifying itfrom time to time. Heretofore many materials have been tried. Universally these embodied a suitable reinfo cotton fabric, which has been impregnated K or any one of a large number of materials, including lacquers, varnishes,

rubber-composition and the like. Asmenbeen emmost eflicient. On the other hand, it is by -far the most expensive. Recently a mixture of viscose and latex has been suggested With one exception, however, namely that 5 of gold beaters skin, the materials lack suffici ent merit to receive serious consideration. I now have found that by using a'solu tion of cellulose, such for example as viscose, in

1 conjunction with a suitable reinforcing medium, it is possible to produce a material whichis a befitting substitute for gold heaters skin. In practicing my invention in its preferred form, a textile material, such, for example,

as to two ounce cotton fabric is coated with a a viscose solution containing as much as 'sive coat after the one preceding has been al- I generating possible to medium, such as a light directed toward the removal Application filed June 23', 1925. Serial No. 39,151.

a ten percent cellulose. Several coats are applied until the weight of the product aggregates four and a half ounces per square yard. While I prefer to apply each succeslowed to dry, this is not necessary and the material may be appliedby a single dip.

After suflicient cellulose has been applied to give the product the required mass, the resultant film is regenerated with a weak solution of sulphuric acid. During'the m process some. hydrogen sulfide is I have found however that it is prevent. a permanent bubble formation in the film by first treatin the material with a'slightly acidified so ution of sodium sulfate and subsequently passin itw through'the regenerating medium. The a ric isthen washed free of the acid, after whichit is treated with a softening a ent. For this purpose, glycerol, which has. Tren diluted with an equal volume of water, may be employed. It is important during the processing operations to maintain the cloth under a slight tension. In the laboratory this has been eflected by stretching the fabric on a frame before'the initial treatment, while in production it is possible to utilize any tensioningdevices for stretchin the fabric, such as a tentering machine, wel known in the textile and dye industries.

The regenerating action is a henomenon liberated.

initial step is one of a settin action together with a gelatinization and dc ydration and is of the solvent. It may be effected by utilizing any one of a large variety of materials and while I have suggested sul huric acid, man other ma--.

terials may a employed. T ese include sodium bisulfite, formic acid,-s odium-acidsulfate, meta-bisulfite and numerous others. Furthermore, as in the manufacture of artificial silk, the cellulose may be regenerated from the viscose solution by employing a progressively more concentrated coagulatln medium. I have found the tensile strengt and durability ofthe product is thereby improved. 4

I-n setting forth the details of the invention, viscose has been referred to as an example of asolution of cellulose. The invention of a course is not limited to this specific substance I inasmuchas cuprammonium or zinc chloride solutions are available substitutes for the up xanthate. It will also be appreciated that the incorporation of pigments, fillers or dye materials is clearly within the scope of the invention.

The product so formed is particularly adapted to be used in rigid dirigibles. On the other hand, it is not so limited but may be used in semi-rigid and non-rigid constructions'as well as ordinary balloons. In utiliz-' ing the fabric for this purpose the sheets of material may be joined by an ordinary glue spice, after which the gas cell may be varnished according to well established proce-- subjected to other variations without de-f xant-hate containing a material inhibiting the formation of hydrogen sulphide bubbles, and

re-generating the cellulose to form a uniform coating upon the fabric.

' 2. The method of treating balloon fabric which comprises coating the ,fabric with a solution of cellulose xanthate containing acidified sodium sulphate and regenerating WILLIAM J. KELLY. 

